1. The Field of the Invention
This invention relates to a speculum for dilating, visualising and instrumenting a body cavity such as a vagina or rectum.
2. Background to the Invention
A conventional speculum comprises a plurality of dilator members or arms which are spread by an actuator for enlarging a body cavity. There are commonly two types of actuators, the lever type and the cam or iris type. The lever type actuator typically comprises a pair of handles each having one dilator arm arranged in a manner so that when the handles are squeezed together the dilator arms spread apart. An inherent drawback with most lever type speculums is that the levers or handles are disposed in the line of sight of the body cavity therefore obscuring a view of the cavity under examination and/or interfering with the placement of medical instruments.
In the iris type speculums, the dilator arms are moved outwardly in a spiralling motion. As a result, the arms must slide against the tissue in the cavity being examined which may cause pinching of the tissue or discomfort to the patient. A further disadvantage with the known iris type speculums is their relatively complex construction and manufacture which increases costs to the extent that the speculums are in general, intended for multiple use. This therefore necessitates a strict hygiene and sterilisation program to ensure that there is no cross infection between patients. Accordingly, the use of iris type speculums is generally inconvenient to practitioners and increases the cost of service.
A further generation of speculums is known in which a rotating annular cam bears against the side of pivotal dilator arms causing the arms to pivot outwardly. An example of such a speculum is shown in Applicant""s International application no. PCT/AU96/00125 (WO 96/28083). While this type of speculum has several advantages over the lever and iris type speculums described above, it is still relatively complex in manufacture requiring the production of numerous separate components which must then be assembled into the complete speculum.
It is an object of the present invention to provide a speculum which is inexpensive to manufacture and assemble and thus can be produced economically to facilitate once only disposable use and does not adversely affect visualisation or instrumenting of a body cavity.
According to the present invention there is provided a speculum body for dilating a body cavity, said speculum including at least:
a main body;
a plurality of first dilator fingers, each of said first fingers having a proximal end and a distal end, said first dilator fingers hinged at their proximal ends to said main body about respective canted hinge axes to allow said first dilator fingers to move with a combined upward and sideways motion; and
an actuator pivotally coupled to said main body so that said actuator can be pivoted into abutment with said first dilator fingers to cause said first dilator fingers to move outwardly with said combined upward and sideways motion thereby dilating said body cavity.
Preferably a short rib is provided on an inside surface adjacent said proximal end of each of said first dilator fingers, said rib being engaged by said actuator to effect said abutment of said actuator with said first dilator fingers.
Preferably each rib is provided with a recess for receiving said actuator when said actuator is pivoted into abutment with said first fingers.
Preferably said rib and said hinge axis of a corresponding first dilator finger are offset from each other in a direction transverse to a longitudinal axis of said corresponding finger.
Preferably said hinge axis and said rib of corresponding finger are disposed on opposite sides of said longitudinal axis of said corresponding finger.
Preferably said main body includes a first ring-like structure to which said first dilator fingers are hinged and said actuator comprises a second ring-like structure which pivots inside said first ring-like structure, said first and second ring-like structures defining a window through which said cavity can be viewed when said actuator is pivoted into abutment with said first dilator fingers.
Preferably the speculum further includes a second dilator finger located between adjacent first dilator fingers, said second dilator finger having a proximal end attached to said actuator, a distal end spaced from said proximal end, and opposite lateral edges extending between said proximal end and said distal end, said distal end of said second dilator finger extending beyond said distal end of said first dilator fingers.
Preferably the speculum further includes a third dilator finger coupled to said main body and located between adjacent first dilator fingers opposite said second dilator finger, said third dilator finger having a distal end that extends beyond said distal end of said first dilator fingers and said distal end of said second dilator finger.
Preferably said third dilator finger is coupled by an integral hinge to said main body.
Preferably said actuator pivots through a first angle prior to abutment with said first dilator fingers so that said second finger commences to move before said first dilator fingers.
Preferably the speculum further includes a releasable locking mechanism for locking said fingers in a desired juxtaposition and subsequently releasing said fingers.
Preferably said releasable locking mechanism includes a first component provided on said actuator and a second component provided on said main body, said first and second components arranged to engage each other when said actuator is pushed in a direction of insertion of said speculum into said body cavity, and released from each other when a force is applied to said actuator to a direction oblique to said direction of insertion.
Preferably said first component comprises one of a pawl and a rack of teeth-like projections, and the second component comprises the other of the pawl and the rack, said pawl and rack being biased into engagement when said actuator is pushed in said direction of insertion, and lifted apart to effect disengagement when said force is applied.